AP Physics 1 Question 80: Answer and Explanation

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Question: 80

10. Pretend someone actually managed to dig a hole straight through the center of the Earth all the way to the other side. If an object were dropped down that hole, which of the following would best describe its motion? Assume ideal conditions and that the object cannot be destroyed.

  • A. It would fall to the center of the Earth and stop there.
  • B. It would fall through the hole to the other side, continue past the opposite side’s opening, and fly into space.
  • C. It would oscillate back and forth from one opening to the other indefinitely.
  • D. It would fall to the other side and stop there.

Correct Answer: C


C This situation is equivalent to a spring-block system. It would start with some potential energy at one extreme edge, turn all of that energy into kinetic energy as it moved to the center, and continue to the other edge due to its momentum (turning the energy back into potential energy). This process would continue indefinitely in ideal conditions.